/**
 * Copyright (C) 2010-2013 Alibaba Group Holding Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.rocketmq.example.simple;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import com.alibaba.rocketmq.client.consumer.DefaultMQPullConsumer;
import com.alibaba.rocketmq.client.consumer.PullResult;
import com.alibaba.rocketmq.client.exception.MQClientException;
import com.alibaba.rocketmq.common.message.MessageQueue;

/**
 * PullConsumer，订阅消息
 */
public class PullConsumer {
	private static final Map<MessageQueue, Long> offseTable = new HashMap<MessageQueue, Long>();

	public static void main(String[] args) throws MQClientException {
		DefaultMQPullConsumer consumer = new DefaultMQPullConsumer("please_rename_unique_group_name_5");

		consumer.start();

		// 1、调用DefaultMQPullConsumer.fetchSubscribeMessageQueues(String topic)方法，根据topic获取对应的MessageQueue（即可被订阅的队列），
		// 在该方法中最终通过调用MQAdminImpl.fetchSubscribeMessageQueues(String topic)方法从NameServer获取该topic的MessageQueue
		Set<MessageQueue> mqs = consumer.fetchSubscribeMessageQueues("TopicTest");
		for (MessageQueue mq : mqs) {
			// 依次从各个队列拉取消息
			System.out.println("Consume from the queue: " + mq);
			SINGLE_MQ : while (true) {
				try {
					PullResult pullResult = consumer.pullBlockIfNotFound(mq, null, getMessageQueueOffset(mq), 32);
					System.out.println(pullResult);
					putMessageQueueOffset(mq, pullResult.getNextBeginOffset());
					switch (pullResult.getPullStatus()) {
						case FOUND :
							// TODO
							break;
						case NO_MATCHED_MSG :
							break;
						case NO_NEW_MSG :
							System.out.println("当前队列没有新消息啦");
							break SINGLE_MQ;
						case OFFSET_ILLEGAL :
							break;
						default :
							break;
					}
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}

		consumer.shutdown();
	}

	private static void putMessageQueueOffset(MessageQueue mq, long offset) {
		offseTable.put(mq, offset);
	}

	private static long getMessageQueueOffset(MessageQueue mq) {
		Long offset = offseTable.get(mq);
		if (offset != null)
			return offset;

		return 0;
	}

}
